Method for ablating interior sections of the tongue

ABSTRACT

A method for reducing a volume of a tongue provides an ablative agent source. The ablative agent source is coupled to an ablative agent delivery device. At least a portion of the ablative agent delivery device is advanced into an interior of the tongue. A sufficient amount of an ablative agent is delivered from the ablative agent delivery device into the interior of the tongue to debulk a section of the tongue without damaging a hypoglossal nerve. Thereafter, the ablative agent delivery device is retracted from the interior of the tongue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 08/651,800, entitled "Method and Apparatus for Treatment of AirWay Obstructions", filed May 22, 1996, and still pending, which is acontinuation-in-part application of allowed U.S. patent application Ser.No. 08/642,053, entitled "Method for Treatment of Airway Obstructions",filed May 3, 1996, which is a continuation-in-part application of U.S.patent application Ser. No. 08/606,195, filed Feb. 23, 1996, entitled"Method for Treatment of Airway Obstructions", now U.S. Pat. No.5,707,349 which cross-references U.S. patent application Ser. No.08/516,781 filed Aug. 18, 1995, entitled "Ablation Apparatus and Systemfor Removal of Soft Palate Tissue", now U.S. Pat. No. 5,674,191 havingnamed inventors Stuart D. Edwards, Edward J. Gough and David L.Douglass, which is a continuation-in-part of U.S. application Ser. No.08/239,658, filed May 9, 1994, now U.S. Pat. No. 5,456,662 entitled"Method for Reducing Snoring by RF Ablation of the Uvula", allincorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method for the treatment of air wayobstructions, and more particularly to a method for ablating selectedtissue sites in an interior of the tongue without damaging thehypoglossal nerve using ablation energy and/or an ablative agent.

2. Description of Related Art

Sleep-apnea syndrome is a medical condition characterized by daytimehypersomnomulence, morning arm aches, intellectual deterioration,cardiac arrhythmias, snoring and thrashing during sleep. It is caused byfrequent episodes of apnea during the patient's sleep. The syndrome isclassically subdivided into two types. One type, termed "central sleepapnea syndrome", is characterized by repeated loss of respiratoryeffort. The second type, termed obstructive sleep apnea syndrome, ischaracterized by repeated apneic episodes during sleep resulting fromobstruction of the patient's upper airway or that portion of thepatient's respiratory tract which is cephalad to, and does not include,the larynx.

Treatment thus far includes various medical, surgical and physicalmeasures. Medical measures include the use of medications such asprotriptyline, medroxyprogesterone, acetazolamide, theophylline,nicotine and other medications in addition to avoidance of centralnervous system depressants such as sedatives or alcohol. The medicalmeasures above are sometimes helpful but are rarely completelyeffective. Further, the medications frequently have undesirable sideeffects.

Surgical interventions have included uvulopalatopharyngoplasty,tonsillectomy, surgery to correct severe retrognathia and tracheostomy.In one procedure the jaw is dislodged and pulled forward, in order togain access to the base of the tongue. These procedures may be effectivebut the risk of surgery in these patients can be prohibitive and theprocedures are often unacceptable to the patients.

Physical measures have included weight loss, nasopharyngeal airways,nasal CPAP and various tongue retaining devices used nocturnally. Thesemeasures may be partially effective but are cumbersome, uncomfortableand patients often will not continue to use these for prolonged periodsof time. Weight loss may be effective but is rarely achieved by thesepatients.

In patients with central sleep apnea syndrome, phrenic nerve ordiaphragmatic pacing has been used. Phrenic nerve or diaphragmaticpacing includes the use of electrical stimulation to regulate andcontrol the patient's diaphragm which is innervated bilaterally by thephrenic nerves to assist or support ventilation. This pacing isdisclosed in Direct Diaphragm Stimulation by J. Mugica et al. PACE vol.10 January-February 1987, Part II, Preliminary Test of a MuscularDiaphragm Pacing System on Human Patients by J. Mugica et al. fromNeurostimulation: An Overview 1985 pp. 263-279 and Electrical Activationof Respiration by Nochomovitez IEEE Eng. in Medicine and Biology; June,1993.

However, it was found that many of these patients also have some degreeof obstructive sleep apnea which worsens when the inspiratory force isaugmented by the pacer. The ventilation induced by the activation of thediaphragm also collapses the upper airway upon inspiration and draws thepatient's tongue inferiorly down the throat choking the patient. Thesepatients then require tracheostomies for adequate treatment.

A physiological laryngeal pacemaker as described in PhysiologicalLaryngeal Pacemaker by F. Kaneko et al. from Trans Am Soc Artif InternOrgans 1985 senses volume displaced by the lungs and stimulates theappropriate nerve to open the patient's glottis to treat dyspnea. Thisapparatus is not effective for treatment of sleep apnea. The apparatusproduces a signal proportional in the displaced air volume of the lungsand thereby the signal produced is too late to be used as an indicatorfor the treatment of sleep apnea. There is often no displaced air volumein sleep apnea due to obstruction.

One measure that is effective in obstructive sleep apnea istracheostomy. However, this surgical intervention carries considerablemorbidity and is aesthetically unacceptable to many patients. Othersurgical procedures include pulling the tongue as forward as possibleand surgically cutting and removing sections of the tongue and otherstructures which can close off the upper airway passage.

A need exists for a method to treat obstructive sleep apnea withoutmajor surgical intervention. A further need exists for a method toablate selected interior sections of the tongue without damaging thehypoglossal nerve with the use of ablative energy and/or an ablativeagent.

SUMMARY OF THE INVENTION

Accordingly, an object of the invention is to provide a method to reducea volume of a selected site in an interior of the tongue withoutdamaging the hypoglossal nerve.

Another object of the invention is to provide a method for ablatingselected sections of the interior of the interior of the tongue withoutdamaging the hypoglossal nerve by the delivery of ablation energy or anablative agent to the selected tissue site.

These and other objects of the invention are achieved in a method forreducing a volume of a tongue. An ablation apparatus is provided thatincludes a source of ablation energy and an ablation energy deliverydevice. At least a portion of the ablation energy delivery device isadvanced into an interior of the tongue. A sufficient amount of energyis delivered from the energy delivery device into the interior of thetongue to debulk a section of the tongue without damaging a hypoglossalnerve. Thereafter, the ablation energy delivery device is retracted fromthe interior of the tongue.

In another embodiment, an ablative agent source is provided. Theablative agent source is coupled to an ablative agent delivery device.At least a portion of the ablative agent delivery device is advancedinto an interior of the tongue. A sufficient amount of an ablative agentis delivered from the ablative agent delivery device into the interiorof the tongue to debulk a section of the tongue without damaging ahypoglossal nerve. Thereafter, the ablative agent delivery device isretracted from the interior of the tongue.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view of an debulking apparatus used with thepresent invention.

FIG. 2 is cross-sectional view illustrating the catheter and connectorof the debunking apparatus shown in FIG. 1.

FIG. 3 is a perspective view of the connector illustrated in FIG. 1.

FIG. 4 is a perspective view of an ablation source delivery deviceassociated with the debulking apparatus illustrated in FIG. 1.

FIG. 5 is a perspective view of a flexible ablation source deliverydevice utilized with the methods of the present invention.

FIG. 6 illustrates the creation of ablation zones with the debulkingapparatus shown in FIG. 1.

FIG. 7 is a cross-sectional view of the tongue with the mouth closed.

FIG. 8 is a cross-sectional view of the tongue with the mouth open.

FIG. 9 is a perspective view of the tongue.

FIG. 10 is a perspective view of the dorsum of the tongue.

FIG. 11 is a cross-sectional view of the tongue.

FIG. 12 is a cross-sectional view of the tongue illustrating thelocation of the hypoglossal nerves and the creation of an ablation zone.

FIG. 13 is a cross-sectional view of the tongue illustrating a pluralityof ablation zones.

FIG. 14 is a perspective view of the ventral surface of the tongue.

FIG. 15 is a cross-sectional view of the tongue.

FIG. 16 is a block diagram of a feedback control system useful with themethods of the present invention.

FIG. 17 is a block diagram illustrating an analog amplifier, analogmultiplexer and microprocessor used with the feedback control system ofFIG. 17.

FIG. 18 is a block diagram of a temperature/impedance feedback systemthat can be used to control cooling medium flow rate through thecatheter of FIG. 1.

FIG. 19 is a three dimensional graph illustrating the percent shrinkageof the tongue following RF ablation.

FIG. 20 is a graph illustrating two-dimensional shrinkage of bovinetongue tissue with RF ablation.

FIG. 21 is a graph illustrating three-dimensional shrinkage of bovinetongue tissue due to RF ablation.

FIG. 22 is a graph illustrating percent volume change in a tonguefollowing RF ablation.

DETAILED DEFSCRIPTION

Referring to FIGS. 1 and 2, a debunking apparatus 10, creatingcontrolled cell necrosis and a reduction of a volume of a selectedtissue site including but not limited to the tongue, lingual tonsils,and/or soft palate tissue, including but not limited to the uvula, isillustrated. Debulking apparatus 10 can be positioned so that one ormore ablation source delivery devices 12, including but not limited todevices that deliver ablation energy and/or an ablative agent withchemical ablation with any number of different compositions and mixturesto create an ablation, alcohol ablation, diode laser ablation, laserfiber (defused) ablation, chemotherapy coupled with ablation, microwave(915 MHz and 2.45 GHz), ultrasound, thermal ablation or cyro ablationusing a hot or very cold solution, solid or gas delivered by infusionsuch as through a needle, and RF at all relevant frequencies, deliverthe ablation energy and/or ablative agent to a selected tissue site andcreate a desired ablation. Each ablation source delivery source 12 isintroduced into an interior of the tongue through a surface of thetongue. Debulking apparatus 10 may include traumatic intubation with orwithout visualization, provide for the delivery of oxygen oranesthetics, and can be capable of suctioning blood or other secretions.It will be appreciated that debulking apparatus 10 is used to treat avariety of different obstructions in the body where passage of gas isrestricted. One embodiment is the treatment of sleep apnea usingablation source delivery device 12 to ablate (create cell necrosis) atselected portions of the tongue, lingual tonsils and/or adenoids by theuse of a variety of different energy sources including but not limitedto resistive heating, RF, microwave, ultrasound and liquid thermal jet.The preferred energy source is an RF source. In this regard, debulkingapparatus 10 can be used to ablate targeted masses including but notlimited to the tongue, tonsils, turbinates, soft palate tissues, hardtissue and mucosal tissue. In one embodiment, debulking apparatus 10 isused to ablate an interior region of the tongue, causing it to becomedebulked in order to increase the cross-sectional area of the airwaypassage. A disinfectant medium introduction member introduces adisinfectant medium in the oral cavity in order to reduce infection ofthe ablated body member.

Prior to debulking the tongue, a presurgical evaluation may be performedincluding a physical examination, fiber optic pharyngoscopy,cephalometric analysis and polygraphic monitoring. The physicalexamination emphasizes the evaluation of the head and neck. It alsoincludes a close examination of the nasal cavity to identify obstructingdeformities of the septum and turbinate; oropharyngeal obstruction froma long, redundant soft palate or hypertrophic tonsils; andhypopharyngeal obstruction from a prominent base of the tongue.

Debulking apparatus 10 includes a catheter 14, an optional handle 16 andone or more ablation source delivery device 12 extending from differentports 18 formed along a longitudinal surface of catheter 14, or from adistal portion of ablation source delivery device 12 Catheter 14 can bea handpiece. An ablation source delivery device advancement device 20may be provided. Ablation source delivery device advancement device 20can include guide tracks or tubes 23 positioned in the interior ofcatheter 14. Ablation source delivery device 12 may be positioned inguide tracks 23 and advanced from the guide tracks into the interior ofthe tongue. Cabling is coupled to ablation source delivery device 12.

Controlled volumetric reduction of the tongue, under feedback control isused to achieve an effective opening in the airway passage. A variety ofdifferent pain killing medicaments, including but not limited toXylocaine, may be used. A digital ultrasonic measurement system can beused. The ultrasound measurement quantifies biological shape changes,provides ultrasonic transmission and reception, uses piezoelectrictransducers (crystals) and provides time of flight data.

A disinfectant medium introduction member 21 may be included andintroduced into the oral cavity. Disinfectant medium introduction member21 can be introduced before, after or during the introduction ofdebulking apparatus 10 into the oral cavity. Additionally, disinfectantmedium introduction member 21 can be removed at the same time or at adifferent time that debunking apparatus 10 is removed from the oralcavity. Disinfectant medium introduction member 21 can be included indebulking apparatus 10, in an interior of catheter 14 or at an exteriorof catheter 14, and may be an introducer with a lumen configured tointroduce a disinfectant agent from a disinfectant agent source 23 intoall or a selected portion of the oral cavity. Disinfectant mediumintroduction member 21 can be capable of movement within the oral cavityin order to provide for disinfection of all or only a portion of theoral cavity. For purposes of this disclosure, the oral cavity is thatbody internal environment where infectious germs may be introduced intothe ablated tongue, soft tissue structure, and the like. Disinfectantmedium introduction member 21 may be slideably positioned in catheter 14or at its exterior. Alternatively, disinfectant medium introductionmember 21 can be an optical fiber coupled to a light energy source,including but not limited to a UV source 25. The optical fiber can alsobe slideably be positioned in the oral cavity. The optical fiber isconfigured to provide for the selective disinfection of all or only aportion of the oral cavity and can have a variety of different distalends to achieve this purpose.

Suitable disinfectant agents include but are not limited to Peridex, anoral rinse containing 0.12% chlorhexidine glucinate(1,1'-hexanethylenebis 5-(p-chlorophenyl)biganide}di-D-gluconate in abase containing water, 11.6% alcohol, glycerin, PEG 40 sorbitanarisoterate, flavor, dosium saccharin, and FD&C Blue No. 1.

It will be appreciated that a variety of different disinfectants can beemployed, including other electromagnetic wavelengths, and variouschemical compositions. The disinfectant medium can be introduced priorto ablation, during ablation and/or after the ablation. It can bedelivered continuously. The level of disinfection of the oral cavity isselectable as is the volume of the oral cavity that is disinfected. Thedegree of disinfection varies. Disinfection is provided to reduceinfection of the ablated body structure.

Ablation source delivery device 12 may be least partially positioned inan interior of catheter 14. In one embodiment, ablation source deliverydevice 12 is advanced and retracted through a port 18 formed in anexterior surface of catheter 14. Ablation source delivery deviceadvancement and retraction device 20 advances ablation source deliverydevice 12 out of catheter 14, into an interior of a body structure andcan also provide a retraction of ablation source delivery device 12 fromthe interior of the body structure. Although the body structure can beany number of different structures, the body structure will hereafter bereferred to as the tongue. Ablation source delivery device 12 pierce anexterior surface of the tongue and are directed to an interior region ofthe tongue. Sufficient ablation energy is delivered by ablation source12 to the interior of the tongue to cause the tongue to becomesufficiently ablated and debulked. Ablation source delivery device 12can be a hollow structure that is, (i) adapted to deliver differentchemicals to a selected tongue interior ablation site (for chemicalablation) (ii) deliver alcohol or other liquids or semi-liquids toachieve ablation as well as a variety of different infusion mediums,including but not limited to saline, chemotherapy and the like.Different modalities can be combined to achieved a desired ablationincluding but not limited to RF and chemotherapy, chemical andchemotherapy. Ablation source delivery device 12 may have a limitedtravel distance in the tongue. In one embodiment with RF electrodes,this is achieved with an insulation sleeve that is in a surroundingrelationship to an exterior of an electrode. Other devices can include astructure located on ablation source delivery device 12 which limitstheir advancement, or a structure coupled to a catheter which limits theadvancement of ablation source delivery devices 12, such as a stop andthe like.

Ablation source delivery device 12 can include a central lumen forreceiving a variety of fluids that can be introduced into the interiorof the tongue, as well as a plurality of fluid delivery ports. In oneembodiment, the disinfectant agent is introduced through ablation sourcedelivery device 12 into the interior of the selected body structure. Onesuitable fluid is an electrolytic solution. Instead of direct contactwith tissue and ablation source delivery source 12 for the delivery ofablation energy and/or ablative agent, a cooled electrolytic solutioncan be used to deliver the ablation energy and/or ablative agent to thetissue. The electrolytic solution may be cooled in the range of about 30to 55 degrees C.

Catheter 14 includes a catheter tissue interface surface 22, a coolingmedium inlet conduit 24 and a cooling medium exit conduit 26 extendingthrough an interior of catheter 14. Ports 18 are formed in the exteriorof catheter 14, and are preferably formed on catheter tissue interfacesurface 22. Ports 18 are isolated from a cooling medium flowing in inletand outlet conduits 24 and 26. Cooling medium inlet and exit conduits 24and 26 are configured to provide a cooled section of catheter tissueinterface surface 22 of at least 1 to 2 cm². In one embodiment, thecooled section of catheter tissue interface surface 22 is at least equalto the cross-sectional diameter of the underlying zone of ablation. Inanother embodiment, the cooled section of catheter tissue interfacesurface 22 only provides cooling to an area associated with eachdeployed ablation source delivery device.

The size of the cooled section of catheter tissue interface surface 22varies for each patient. The size is sufficient enough to minimizeswelling of the tongue following the delivery of the ablation creationsource. The reduction of swelling can be 50% or greater, 75% or greater,and 90% and greater. The amount of cooling provided is sufficient toenable the patient to return home shortly after the debulking procedureis performed, and not run the risk of choking on the tongue. It has beenfound that by providing a sufficient level of cooling over a relativelylarge area, the amount of ablation in an interior region of the tongueis enhanced. By providing a sufficiently large enough cooled section ofcatheter tissue interface surface 22, an adenomas response is minimized.

An ablation delivery surface 30 of ablation source delivery device 12can be adjusted by inclusion of an adjustable or non-adjustableinsulation sleeve 32 (FIGS. 3, 4, and 5). Insulation sleeve 32 can beadvanced and retracted along the exterior surface of ablation sourcedelivery device 12 in order to increase or decrease the length of theablation delivery surface 30. Insulation sleeve 32 can be made of avariety of materials including but not limited to nylon, polyimides,other thermoplastics and the like. The size of ablation delivery surface30 can be varied by other methods including but not limited to creatinga segmented ablation source delivery device 12 with a plurality ofsections that are capable of being multiplexed and individuallyactivated, and the like.

Referring specifically to FIG. 4, ablation source delivery device 12 hasan advancement length 33 that extends from an exterior surface ofcatheter 14 and is directed into the interior of the tongue. Advancementlength 33 is sufficient to position ablation delivery surface 30 at aselected tissue site in the interior of the tongue. Ablation deliverysurface 30 is of sufficient length so that the ablation energy isdelivered to the selected tissue site, create a desired level ofablation (cell necrosis) at the selected tissue site without causingdamage to the hypoglossal nerve. Ablation delivery surface 30 is notalways at the distal end of ablation source delivery device 12.Insulation 32 can also be positioned at the distal end of ablationsource delivery device 12. In this embodiment, ablation delivery surface30 does not extend to the distal end of ablation source delivery device12. However, ablation delivery surface 30 still delivers sufficientablation energy to create a desired level of cell necrosis in theinterior of the tongue at the selected tissue site without damaging thehypoglossal nerve and/or damage to the surface of the tongue.Additionally, only one side or a portion of a side of ablation sourcedelivery device 12 can be insulated. This also provides for an ablationsource delivery device 12 which can be positioned throughout the tongue,including adjacent to a hypoglossal nerve. Where ablation sourcedelivery device 12 is adjacent to the hypoglossal nerve, ablation sourcedelivery device 12 is insulated.

In one embodiment, advancement length 33 is 1.2 to 1.5 cm, and thelength of ablation delivery surface 30 is 5 to 10 mm, more preferablyabout 8 mm.

In another embodiment, advancement length 33 is insufficient to reachthe hypoglossal nerve when introduced through any of the tonguesurfaces, particularly the dorsum of the tongue.

Ablation source delivery device advancement device 20 is configured toadvance at least a portion of each ablation source delivery device 12 toa placement position in the interior of the tongue. Ablation sourcedelivery device advancement device 20 can also be configured to retracteach ablation source delivery device 12. At the placement position,ablation delivery surface delivers sufficient ablation energy and/oreffect to reduce a volume of the selected site without damaging ahypoglossal nerve and/or a surface of the tongue. In one embodiment,ablation source delivery device advancement and retraction device 20,with or without guide tracks 23, directs the delivery of ablation sourcedelivery device 12 from catheter 14 into the interior of the tongue atan angle of 60 to 90 degrees relative to a longitudinal axis of catheter14, and preferably about 70 degrees.

In certain embodiments, ablation source delivery device 12 has ageometric shape, including but not limited to a curved configurationthat includes one or more insulated surfaces, either partially insulatedon one side, at a proximal end, at a distal end, and the like, that isconfigured to reduce the volume of the selected tissue site withoutdamaging a hypoglossal nerve. In one embodiment, ablation sourcedelivery device 12 is introduced through any tongue surface and isconfigured so that a section of ablation source delivery device 12 whichmay be positioned close to the hypoglossal nerve is provided withinsulation 32. As previously noted, insulation 32 can be positioned atdifferent sites of ablation source delivery device 12.

Handle 16 is preferably made of an insulating material. Ablation sourcedelivery device 12 may be made of a conductive material such asstainless steel. Additionally, ablation source delivery device 12 can bemade of a shaped memory metal, such as nickel titanium, commerciallyavailable from Raychem Corporation, Menlo Park, Calif. In oneembodiment, only a distal end of ablation source delivery device 12 ismade of the shaped memory metal in order to effect a desired deflection.When introduced into the oral cavity, catheter 14 can be advanced untila patient's gag response is initiated. Catheter 14 is then retractedback to prevent patient's gagging. The distal end of ablation sourcedelivery device 12 can be semi-curved. The distal end can have ageometry to conform to an exterior of the tongue.

In one embodiment of the invention catheter 14 is a handpiece and shallfor purposes of this invention catheter 14 shall be referred to as("handpiece 14"). In this embodiment, a separate handle 16 is notnecessary. Debulking apparatus 10 is used to treat an interior region ofthe tongue. Handpiece 14 has a distal end that is sized to be positionedwithin an oral cavity. Ablation source delivery device 12 is at leastpartially positioned within an interior of handpiece 14. Ablation sourcedelivery device 12 includes an ablation delivery surface 30. Ablationsource delivery device advancement member 20 is coupled to ablationsource delivery device 12 and calibrated to advance ablation sourcedelivery device 12 from handpiece 20, including but not limited to adistal end of handpiece 20, into the interior of the tongue whenhandpiece 20 is positioned adjacent to a surface of the tongue. Ablationsource delivery device 12 is advanced an advancement distance 33 fromhandpiece 20 of sufficient length to treat the interior region of thetongue with ablation energy and/or an ablative agent without damagingthe hypoglossal nerve or the surface of the tongue.

Catheter 14 can be malleable in order to conform to the surface of thetongue when a selected ablation target site is selected. An encapsulatedsoft metal, such as copper, or an annealed metal/plastic material can beused to form malleable catheter 14. All or a portion of catheter 14 maybe malleable or made of a shaped memory metal.

For many applications it is desirable for a distal end 14' of catheter14 to be deflectable. This can be achieved mechanically or with the useof memory metals. A steering wire, or other mechanical structure, can beattached to either the exterior or interior of distal end 14'. In oneembodiment, a deflection knob located on handle 16 is activated by thephysician causing a steering wire to tighten. This imparts a retractionof distal end 14', resulting in its deflection. It will be appreciatedthat other mechanical devices can be used in place of the steering wire.The deflection may be desirable for tissue sites with difficult access.

Handle 6 can comprise a connector 34 coupled to retraction andadvancement device 20. Connector 34 provides a coupling of a ablationsource delivery device to power, feedback control, temperature and/orimaging systems. An RF/temperature control block 36 can be included.

In one embodiment, the physician moves retraction and advancement device20 in a direction toward a distal end of connector 34. Ablation sourcedelivery device 12 can be spring loaded. When ablation source deliverydevice advancement device 20 is moved back, springs cause selectedablation source delivery devices 12 to advance out of catheter 14.

One or more cables 38 may be coupled to ablation source delivery device12 to an energy source 40. A variety of energy sources 40 can be usedwith the present invention to including but not limited to RF,microwave, ultrasound, coherent light, incoherent light, ultrasound,chemical ablation, alcohol ablation, thermal transfer, thermal jet,chemotherapy combined with RF, and other combinations of these sources.Preferably, energy source 40 is a RF generator. When a RF energy sourceis used, the physician can activate RF energy source 40 by the use of afoot switch (not shown) coupled to RF energy source 40.

One or more sensors 42 may be positioned on an interior or exteriorsurface of ablation source delivery device 12, insulation sleeve 32, orbe independently inserted into the interior of the body structure.Sensors 42 permit accurate measurement of temperature at a tissue sitein order to determine, (i) the extent of ablation, (ii) the amount ofablation, (iii) whether or not further ablation is needed, and (iv) theboundary or periphery of the ablated geometry. Further, sensors 42prevent non-targeted tissue from being destroyed or ablated.

Sensors 42 are of conventional design, including but not limited tothermistors, thermocouples, resistive wires, and the like. Suitablesensors 42 include a T type thermocouple with copper constantene, Jtype, E type, K type, fiber optics, resistive wires, thermocouple IRdetectors, and the like. It will be appreciated that sensors 42 need notbe thermal sensors.

Sensors 42 measure temperature and/or impedance to permit ablationmonitoring. This reduces damage to tissue surrounding the targetedablation mass. By monitoring the temperature at various points withinthe interior of the body structure the periphery of ablation can beascertained and it is possible to determine when the ablation iscompleted. If at any time sensor 42 determines that a desired ablationtemperature is exceeded, then an appropriate feedback signal is receivedat energy source 40 and the amount of energy delivered is regulated.

Debulking apparatus 10 can include visualization capability includingbut not limited to a viewing scope, an expanded eyepiece, fiber optics,video imaging, and the like.

Additionally, ultrasound imaging can be used to position the ablationsource delivery device 12 and/or determine the amount of ablation. Oneor more ultrasound transducers 44 can be positioned in or on ablationsource delivery device 12, catheter 14, or on a separate device. Animaging probe may also be used internally or externally to the selectedtissue site. A suitable imaging probe is Model 21362, manufactured andsold by Hewlett Packard Company. Each ultrasound transducer 44 iscoupled to an ultrasound source (not shown).

With reference now to FIG. 6 catheter 14 is shown as being introducedinto the oral cavity and multiple ablation source delivery devices 12are advanced into the interior of the tongue creating different ablationzones 46. Using RF, Debulking apparatus 10 can be operated in eitherbipolar or monopolar modes. In FIG. 6, ablation source delivery deviceis an RF electrode operated in the bipolar mode, creating sufficientablation zones 46 to debulk the tongue without affecting the hypoglossalnerves and creating a larger airway passage. With this debulking, theback of the tongue moves in a forward direction away from the airpassageway. The result is an increase in the cross-sectional diameter ofthe air passageway.

Using RF, debulking apparatus 10 can also be operated in the monopolarmode. A groundpad can be positioned in a convenient place such as underthe chin. In this embodiment, a single RF electrode is positioned in thetongue to create a first ablation zone 46. The RF electrode can then beretracted from the interior of the tongue, catheter 14 moved, and the RFelectrode is then advanced from catheter 14 into another interiorsection of the tongue. A second ablation zone 46 is created. Thisprocedure can be completed any number of times to form differentablation regions in the interior of the tongue.

More than one ablation source delivery device 12 can be introduced intothe tongue and operated in the bipolar mode. One or more ablation sourcedelivery devices 12 are then repositioned in the interior of the tongueany number of times to create a plurality of connecting ornon-connecting ablation zones 46.

Referring now to FIGS. 7 through 15, various anatomical views of thetongue and other structures are illustrated. The different anatomicalstructures are as follows: the genioglossus muscle, or body of thetongue is denoted as 48; the geniohyoid muscle is 50; the mylohyoidmuscle is 52; the hyoid bone is 54; the tip of the tongue is 56; theventral surface of the tongue is denoted as 58; the dorsum of the tongueis denoted as 60; the inferior dorsal of the tongue is denoted as 62;the reflex of the vallecula is 64; the lingual follicles are denoted as66; the uvula is 68; the adenoid area is 70; the lateral border of thetongue is 72; the circumvallate papilla is 74, the palatine tonsil is76; the pharynx is 78; the redundant pharyngeal tissue is 80; theforamen cecum is 82; the hypoglossal nerve is 84, and the lingual frenumof the tongue is 86.

Dorsum 60 is divided into an anterior 2/3 and inferior dorsal 62. Thedelineation is determined by circumvallate papilla 74 and foramen cecum82. Inferior dorsal 62 is the dorsal surface inferior to circumvallatepapilla 74 and superior reflex of the vallecula 64. Reflex of thevallecula 64 is the deepest portion of the surface of the tonguecontiguous with the epiglottis. Lingual follicles 66 comprise thelingual tonsil.

Catheter 14 can be introduced through the nose or through the oralcavity. Ablation source delivery device 12 can be inserted into aninterior of the tongue through dorsum surface 60, inferior dorsalsurface 62, ventral surface 58, tip 56 or geniohyoid muscle 50.Additionally, ablation source delivery device 12 may be introduced intoan interior of lingual follicles 66 and into adenoid area 70. Onceablation source delivery device 12 is positioned, insulation sleeve 32,if included, may be adjusted to provided a desired energy deliverysurface 30 for each ablation source delivery device 12.

Ablation zones 46 are created without damaging hypoglossal nerves 84.This creates a larger air way passage and provides a treatment for sleepapnea.

In all instances, the positioning of ablation source delivery device 12,as well as the creation of ablation zones 46 is such that hypoglossalnerves 84 are not ablated or damaged. The ability to swallow and speakis not impaired.

FIG. 16 illustrates placement of ablation source delivery device 12 onthe dorsum surface 60 of the tongue. The first ablation source deliverydevice 12 is positioned 0.5 cm proximal to the circumvallate papilla.The other ablation source delivery devices 12 are spaced 1.6 cm apartand are 1 cm off a central axis of the tongue. In one embodiment, 465MHz RF was applied. The temperature at the distal end of ablation sourcedelivery device 12 was about 100 degrees C. The temperature at thedistal end of the insulation sleeve 32 was about 60 degrees C. Inanother embodiment, the temperature at the distal end of insulationsleeve 32 was 43 degrees C. and above. RF energy can be applied as shortduration pulses with low frequency RF. Precise targeting of a desiredablation site is achieved. One or more ablation source delivery devices12 may be used to create volumetric three-dimensional ablation. Avariety of ablation geometries are possible, including but not limitedto rectilinear, polyhedral, redetermined shapes, symmetrical andnon-symmetrical.

Referring now to FIGS. 17 and 18 an open or closed loop feedback systemcouples sensors 42 to energy source 40. The temperature of the tissue,or of ablation source delivery device 12 is monitored, and the outputpower of energy source 40 adjusted accordingly. Additionally, the levelof disinfection in the oral cavity can be monitored. The physician can,if desired, override the closed or open loop system. A microprocessorcan be included and incorporated in the closed or open loop system toswitch power on and off, as well as modulate the power. The closed loopsystem utilizes a microprocessor 88 to serve as a controller, watch thetemperature, adjust the RF power, look at the result, refeed the result,and then modulate the power.

With the use of sensors 42 and the feedback control system a tissueadjacent to ablation source delivery device 12 can be maintained at adesired temperature for a selected period of time without impeding out.Each ablation source delivery device 20 may be connected to resourceswhich generate an independent output for each ablation source deliverydevice. An output maintains a selected energy at ablation sourcedelivery device 12 for a selected length of time.

When an RF electrode is used, current delivered through the RF electrodeis measured by current sensor 90. Voltage is measured by voltage sensor92. Impedance and power are then calculated at power and impedancecalculation device 94. These values can then be displayed at userinterface and display 96. Signals representative of power and impedancevalues are received by a controller 98. Signals representative of energydelivery for the different ablation sources can also be generated,measured and received by controller 98.

A control signal is generated by controller 98 that is proportional tothe difference between an actual measured value, and a desired value.The control signal is used by power circuits 100 to adjust the poweroutput in an appropriate amount in order to maintain the desired powerdelivered at respective ablation source delivery device 12.

In a similar manner, temperatures detected at sensors 42 providefeedback for maintaining a selected power. The actual temperatures aremeasured at temperature measurement device 102, and the temperatures aredisplayed at user interface and display 96. A control signal isgenerated by controller 98 that is proportional to the differencebetween an actual measured temperature, and a desired temperature. Thecontrol signal is used by power circuits 100 to adjust the power outputin an appropriate amount in order to maintain the desired temperaturedelivered at the respective sensor. A multiplexer can be included tomeasure current, voltage and temperature, at the numerous sensors 42.

Controller 98 can be a digital or analog controller, or a computer withsoftware. When controller 98 is a computer it can include a CPU coupledthrough a system bus. On this system can be a keyboard, a disk drive, orother non-volatile memory systems, a display, and other peripherals, asare known in the art. Also coupled to the bus is a program memory and adata memory.

User interface and display 96 includes operator controls and a display.Controller 98 can be coupled to imaging systems, including but notlimited to ultrasound, CT scanners, X-ray, MRI, mammographic X-ray andthe like. Further, direct visualization and tactile imaging can beutilized.

The output of current sensor 90 and voltage sensor 92 is used bycontroller 98 to maintain a selected power level at the RF electrodes.The amount of RF energy delivered controls the amount of power. Aprofile of power delivered can be incorporated in controller 98, and apreset amount of energy to be delivered can also be profiled. Othersensors similar to sensors 90 and 92 can be used by controller 98 forother ablation source delivery devices 12 to maintain a controllableamount of an ablation energy and/or ablative agent.

Circuitry, software and feedback to controller 98 result in processcontrol, and the maintenance of the selected power that is independentof changes in voltage or current, and are used to change, (i) theselected power, (ii) the duty cycle (on-off and wattage), (iii) bipolaror monopolar energy delivery, and (iv) infusion medium delivery,including flow rate and pressure. These process variables are controlledand varied, while maintaining the desired delivery of power independentof changes in voltage or current, based on temperatures, or othersuitable parameters, monitored at sensors 42.

Current sensor 90 and voltage sensor 92 are connected to the input of ananalog amplifier 104. Analog amplifier 104 can be a conventionaldifferential amplifier circuit for use with sensors 42. The output ofanalog amplifier 104 is sequentially connected by an analog multiplexer106 to the input of A/D converter 108. The output of analog amplifier104 is a voltage which represents the respective sensed temperatures.Digitized amplifier output voltages are supplied by A/D converter 108 tomicroprocessor 88. Microprocessor 88 may be a type 68HCII available fromMotorola. However, it will be appreciated that any suitablemicroprocessor or general purpose digital or analog computer can be usedto calculate impedance or temperature.

Microprocessor 88 sequentially receives and stores digitalrepresentations of impedance and temperature. Each digital valuereceived by microprocessor 88 corresponds to different temperatures andimpedances.

Calculated values, including but not limited to power and impedance, canbe indicated on user interface and display 96. Alternatively, or inaddition to the numerical indication of power or impedance, calculatedimpedance and power values can be compared by microprocessor 88 withpower and impedance limits. When the values exceed predetermined poweror impedance values, a warning can be given on user interface anddisplay 96, and additionally, the delivery energy can be reduced,modified or interrupted. A control signal from microprocessor 88 canmodify the power level supplied by energy source 40.

FIG. 18 illustrates a block diagram of a temperature/impedance feedbacksystem that can be used to control cooling medium flow rate throughcatheter 14. Energy is delivered to ablation source delivery device 12by energy source 44, and applied to tissue. A monitor 110 ascertainstissue impedance, based on the energy delivered to tissue, and comparesthe measured impedance value to a set value. If the measured impedanceexceeds the set value a disabling signal 112 is transmitted to energysource 40, ceasing further delivery of energy to ablation sourcedelivery device 12. If measured impedance, or other measured parameter,is within acceptable limits, energy continues to be applied to thetissue. During the application of energy to tissue sensor 42 measuresthe temperature of tissue and/or ablation source delivery device 12. Acomparator 114 receives a signal representative of the measuredtemperature and compares this value to a pre-set signal representativeof the desired temperature. Comparator 114 sends a signal to a flowregulator 116 representing a need for a higher cooling medium flow rate,if the tissue temperature is too high, or to maintain the flow rate ifthe temperature has not exceeded the desired temperature.

EXAMPLE 1

Debulking apparatus 10 was used to determine two-dimensional shrinkageof a bovine. RF volumetric reduction was achieved using a single needleelectrode. Four mature ultrasonic crystals were positioned to form asquare. Measurements were taken at control and post volumetric reductionat 15 watts initially with a 13% volumetric reduction, and 15 watts for4 hours with an additional 4% volumetric reduction. A total 17%volumetric reduction was achieved.

EXAMPLE 2

Debulking apparatus 10 was used to determine three-dimensional shrinkageof a bovine tongue. RF volumetric reduction was achieved with a singleneedle electrode with eight miniature ultrasonic crystals, creating acube. Application of 16 watts initially produced a 17% volumetricreduction of the tongue, 25 watts applied initially produced a 25%volumetric reduction, and 25 watts after hours produced an additional 4%reduction, for a total volumetric reduction of 29%.

EXAMPLE 3

A 35% volumetric reduction was achieved in porcine in vivo, with threedimensional gross at 20 watts initial application.

Referring now to FIG. 19, ablation volume dimensions were measured witha multidimensional digital sonomicrometry. An average decrease in the Zdirection was 20%, and volume shrinkage was 26%. Three-dimensionalshrinkage of tongue tissue due to in vivo RF ablation with the needle,ablation with 20 Watts) is presented in FIG. 20. Control volume beforeablation is compared with a post-ablation volume.

FIG. 20 illustrates two-dimensional shrinkage of a bovine tongue tissuedue to RF ablation with a needle electrode. The before and afterablation results are illustrated.

FIG. 21 illustrates in graph form ablation at 16 Watts resulted in a 17%volume shrinkage of the tissue in post-ablation verses control. Ablationat 25 watts resulted in a 25% volume shrinkage after ablation. Anadditional 4% area shrinkage was obtained after in long-term postablation (4 hours) verses post-ablation.

FIG. 22 illustrates a percent volume change after RF ablation. 16 Watts,ablation at 16 Watts for 20 minutes; 25 Watts, ablation at 25 Watts for20 minutes; 25 Watts (4 hours), and long tern post ablation (4 hoursafter 25 Watts ablation).

The foregoing description of a preferred embodiment of the invention hasbeen presented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formsdisclosed. Obviously, many modifications and variations will be apparentto practitioners skilled in this art. It is intended that the scope ofthe invention be defined by the following claims and their equivalents.

What is claimed is:
 1. A method for reducing a volume of a tongue,comprising:providing an ablation apparatus including a source ofablation energy and an ablation energy delivery device; advancing atleast a portion of the ablation energy delivery device into an interiorof the tongue; delivering a sufficient amount of energy from the energydelivery device into the interior of the tongue to debulk a section ofthe tongue without permanently damaging a main branch of a hypoglossalnerve; and retracting the ablation energy delivery device from theinterior of the tongue.
 2. The method of claim 1, wherein the energysource is an RF source and the ablation energy delivery device is an RFelectrode.
 3. The method of claim 1, wherein the energy source is acoherent source of light and the ablation energy delivery device is anoptical fiber.
 4. The method of claim 1, wherein the energy source is aheated fluid and the ablation energy delivery device is a catheter witha closed channel configured to receive the heated fluid.
 5. The methodof claim 1, wherein the energy source is a heated fluid and the ablationenergy delivery device is a catheter with an open channel configured toreceive the heated fluid.
 6. The method of claim 1, wherein the energysource is a cooled fluid and the ablation energy delivery device is acatheter with a closed channel configured to receive the cooled fluid.7. The method of claim 1, wherein the energy source is a cooled fluidand the ablation energy delivery device is a catheter with an openchannel configured to receive the cooled fluid.
 8. The method of claim1, wherein the energy source is a cryogenic fluid.
 9. The method ofclaim 1, wherein the energy source is a microwave source providingenergy from 915 MHz to 2.45 GHz and the ablation energy delivery deviceis a microwave antenna.
 10. The method of claim 1, wherein the energysource is an ultrasound source and the ablation energy delivery deviceis an ultrasound emitter.
 11. The method of claim 1, wherein the energysource is a microwave source.
 12. The method of claim 1, wherein theelectrode is advanced into an interior of the tongue through a ventralsurface of the tongue.
 13. The method of claim 1, wherein the ablationenergy delivery device is advanced into an interior of the tonguethrough an inferior dorsal surface of the tongue.
 14. The method ofclaim 1, wherein the ablation energy delivery device is advanced into aninterior of the tongue through a dorsum surface of the tongue.
 15. Themethod of claim 1, wherein the ablation energy delivery device isadvanced into an interior of the tongue through a tip of the tongue. 16.A method for reducing a volume of a tongue, comprising:providing anablative agent source coupled to an ablative agent delivery device;advancing at least a portion of the ablative agent delivery device intoan interior of the tongue; delivering a sufficient amount of an ablativeagent from the ablative agent delivery device into the interior of thetongue to debulk a section of the tongue without permanently damaging amain branch of a hypoglossal nerve; and retracting the ablative agentdelivery device from the interior of the tongue.
 17. The method of claim16, wherein the ablative agent is a chemical composition or mixture ofcompositions.
 18. The method of claim 16, wherein the ablative agentincludes an alcohol composition.
 19. The method of claim 16, wherein theablative agent is a chemotherapeutic agent.
 20. The method of claim 19,further comprising:providing an RF electrode to deliver electromagneticenergy to an interior section of the tongue.